Combined rheostat and heater.



Patented May 20, |902.

M. C. KRUEGER.

- COMBINED BHEOSTAT AND HEATER.

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la lutti im unil WtIl-EEEEE- UNITED STATES PATENT OFFICE.

MAX C. KRUEGER, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGN- MENTS, OF ONE-HALF TO MCGUIRE MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

COMBINED RHEOSTAT AND HEATER.

SPECIFICATION forming part of Letters Paten-t No. 700,207, dated May 20, 1902.

Application filed October 4, 1901. Serial No. 77,538.` (No model.)

To all whom it may concern:

Be it known. that I, MAX C'. KRUEGER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Combined Rheostat and Heater, of which the following is a specification.

This invention relates to a combined rheostat and heater.

The object of the invention is to provide a combined rheostat and heater which is simple land efficient.

A further object of the invention is to provide a combined rheostat and heateremploying a non-corrosive contact and a non-metallic resistance.

Other objects of the invention will appear more fully hereinafter.

The invention consists,substantially,in the construction, combination, location, and arrangement of parts, all as will be more fully hereinafter set forth, as showlrin the accompanying drawings, and finally pointed out in the appended claims.

Referring to the accompanying drawings and to the various views and reference-signs appearing thereon, Figure l is a face view or front elevation of a combined rheostat and heater embodying the principles of my invention. Fig; 2 is a transverse section on the line 2 2, Fig. l, looking in the direction of the arrows. Fig. 3 is aview of the reverse side, as shown in Fig. l, of the insulating slab or plate. Fig. 4 is a view similar to Fig. l, showinga modied construction and arrangement embraced within the spirit and scope of the invention. Fig. 5 is a View similar to Fig. 2 on the line 5 5, Fig. Li, looking in the direction of the arrows. Figs.` 6, 7, 8, and 9 are detail views in section, showing various constructions of non-corrosive contacts embracing the principles of the invention.

'The same part is designated by the same reference-sign wherever it occurs throughout the several views. Y

In the construction of rheostats and electric heaters great difficulty has been expe* rienced by reason of corrosion and oxidation at the contact with the resistance material. Itis the special purpose of the present invention to overcome this difficulty and to provide a non-corrosive contact and to avoid oxidizing the resistance material,especially when used as a heater, and to this end I propose to employ a non metallic resistance material made up of a combination of graphite and clay or other suitable material. This resistance material may be used in the form of a stick or rod, (indicated at A.)

B designates a suitable non-conducting or insulating supportingplate-such, for instance, as marble. Upon this plate the resistance stick or rod is supported.- As shown in Figs. l, 2, and 3, the stick or rod A, of nonmetallic resistance material, is su pported on the rear side ofthe insulating-plate B by means of hangers or supporting-brackets C. At suitable intervals along the length of the resistance stick or rod are arranged contact devices, each in electrical contact with a series of contact-points D, (see Fig. 1,) arranged to project through the insulating-plate B and in cooperating relation with respect to a contact-arm E, pivotally mounted upon a stud or pin F and provided with an operating-handle G, by which said lever E may be swung over and in successive contacting relation with re spect to the contacts D. II designates a spring arranged to normally maintain the arm E in initial or retracted position. This is the construction and arrangement when the invention is applied to a rheostat; but the principles thereof may also be applied in the construction of electric heaters.

As above stated, the difficulty heretofore experienced has been in effecting the proper contacting relation of the contact-points-D with the resistance stick or rod by reason of the oxidation and corrosion, especially when the resistance stick or rod is heated7 and which occurs at the contacts. I overcome this objection in the following manner: At the points in the length of the stick or rod where it is desired to effect electrical connection between such rod and the corresponding contact-points D, I drill a hole through tho resistance stick or rod and insert therethrough a stud or pin J, (see Fig. 7,) one end of said stud or pin being provided with a head l and the other end being threaded, as at L, to receive a clamp-nut M thereon. Interposed between the head K of the pin or stud and the side of the resistance stick or rod A is a disk, plate, or washer N, preferably of aluminium, or nickel-aluminium alloy, or other non-corrosive material. Similarly a disk, plate, or washer O is interposed between the nut M and the side oi' the resistance material.

P designates a nut, also threaded upon the end of the stud or pin J, and thereby forming means for binding a leading-wire thereto, said leading-wire (indicated at Q, Fig. 7) being clamped between the nuts P and M. This leading-wire leads from said contact to the corresponding contact-point D.

In Fig. G I have shown a modified form of contact wherein the head K of the pin or stud J" is enlarged to afford an efficient and increased area of contacting surface with the resistance stick or rod A. Similarly the nut O is correspondingly enlarged for the same purpose. In this form of contact it is preferable that the head K and nut O be of non-corrosive material, and in this case the washers-such as N O, Fig. 7-maybe omitted. The leadingwire @,Fig. G, is clamped, in the same way as above described with respect to Fig. 7, between nut O and a nut P', threaded upon the end of pin or stud J.

ln Fig. 8 l have shown a slightly-modilied construction very similar to the construction shown in Fig. 7, wherein the washers N2 O2 are interposed, respectively, between the head K2 and nut M2 of Contact pin or stud J2', the leading-wire Q being clamped between nut M2 and a nut P2 in the same manner as above described.

In Fig. 9 another slightly-modified arrangement is shown wherein in order to increase the contacting or bearing surface the washers N3 Os are provided with depending flanges arranged to extend over the edges of the resistance stick or rod A and are clamped into efficient contact with said resistance stick or rod by means of headed pins J5 passing through openings formed through the resistance stick or rod and clamped by means of the clamp-nuts M3 in the manner above described. lf desired, one of these clamp pins or studs may aiord means for effecting electrical connection with the connecting or leading wire, as clearly indicated in Fig. 9.

In the embodiment of my invention as shown in Figs. l, 2, and 3, wherein the resistance-stick is supported upon the under or rear side of the insulating-plate A, I am enabled to inclose the resistance material and the electrical wiring within a box or casing R, suitably bolted or otherwise secured to the insulating-plate, thus exposing merely the front face of the insulating-plate with the series of contact-points D and the contact lever or arm E. By providing the box or casing with suitable supporting tongues or ears S the device may be conveniently supported upon a wall in accessible position for operation.

In Figs. 4- and 5 I have shown a slightlymodified arrangement wherein instead of supporting the resistance stick or rod A upon the under or rear side of the insulating-plate said resistance stick or rod is supported upon the upper or front face of said insulatingplate. In this construction the resistance stick or rod A is preferably curved, with the center of curvature coinciding with the pivotpin F/ of contact arm or lever E', and the series of contact-points D are mounted directly upon the resistance stick or rod, as clearly shown, the contact lever or arm E' operating thereovcr in the same manner as above described. This construction I have Afound efficient i'or the cheaper constructions of rheostats and heaters, inasmuch as it avoids the necessity for providing so many holes through the insulating-plate l5. It is not so desirable, however, for the larger constructions, in that the resistance stick or rod is not closed, and consequently is left exposed. Reference-sign B5 designates a solenoid operating on a suitable armature or core C5 to afford an automatic detent for the contact arm or lever E when swung to the limit of its movement against the action of its retractile H Il.

lVhen the apparatusis employed as a rheostat, contact A5 (see Figs. l and 4) forms the terminal of the line-wire connection from a suitable source of current. D5 designates a connection. from said binding-post to a contact stud or pin E5, which is in electrical connection through the mass with contact arm or lever E E and which may also serve to 'form a limiting-stop for said contact-lever, against which said lever is held by its retractile II l-I. lf desired and in order to relieve any shock which may occur when said contact arm or lever is returned to its initial or retracted position, a buffer F5 may be interposed between said contact arm or lever and said contact-stop G5 designates the contact-terminal for the motor-armature. This contact-terminal is in electrical connection in any suitable manner-as, for instance, by means of the conducting-strip H5, (see Fig. 3)-with the last terminal or contact of the resistance stick or rod A. From contact D5 a wire J5 connects with a contact-point K5, which is in electrical connection with one of the windings of solenoid B5, the other terminal of said winding being connected to a contact L5, which is in electrical connection with a terminal M5 of the motor field-winding. V

The operation when the apparatus is employed as a rheostat is as follows: Currentis supplied from the main line or other source to binding-post A5, thence through connec- IOO IIO

tion D to contact At this point the cn rrent divides, one part continuing through Wire J5 to terminal K5, thence through the solenoid B5 to terminal If, thence to terminal M5, and on through the field of the motor. The other part of the current continues from the terminal E5 through contact lever or arm E E', thence through whichever of the contact-points D may be in electrical connection With said contact arm or lever, thence through the resistance stick or rod A to the last contact thereon, thence to terminal P5, (see Fig. 3,) contact-strip H5, to terminal G5, and the armature of the motor. Thus it will be seen that by varying the position of the contact arm or lever E E/ the amount of resistance material included in the motor-armature circuit may be varied, and When said lever or arm E E is swung to its extreme limit of movement against the action of its retractil@ H-that is, in position for the solenoid core or pin C5 to form a stop therefor-all the resistance is cut out of the armature-circuit. When, however, the strength of the current increases to such extent that the portion thereof Which traverses the motor held-magnets is sufficient to energize the coils of solenoid B5 to such an extent as to withdraw the solenoid-core C5 from engaging relation with respect to the contact arm or lever E E, said lever is released and is returned by its retractile to its initial position.

The same principles as above described, as

is obvious, are equally Well adapted for use in regulating an electric heater, so as to arrest or break the circuit when the current attains any predetermined strength.

It is obvious that the arrangement of the parts iu the adaptation of my invention to rheostats or heaters may be greatly varied Without departure from the spirit and scope of my invention, the essential feature of which is the employment of non-corrosive contacts and a non-metallic resistance material. Vhen, however, the automatic-release solenoid is employed, I prefer to so arrange the parts that the core C5 thereof may be gravity-actuated in a direction to form a limiting-stop or retaining device for the contact arm or lever E E', so that When said lever or arm is swung to its extreme limit of movement it Will ride freely past the projecting end of said core, said projecting end being held in position as a retainer or stop by gravity, and consequently dropping down into engaging position as soon as the arm or lever E E has been swung past it, said stop being released when the solenoid has been sufficiently energized by the current traversing the coils thereof, thereby permitting the contact arm or lever to return to its initial position.

By the construction of nou-corrosive contacts, such as above explained, I secure a most efficient, simple, and economical arrangement and I avoid corrosion and oxidation at the contacts, and hence secure an indeiinite life for the resistance material and wherein the contacts remain unimpaired.

In the form shown in Figs. 4 and 5 it is to be understood that the Washers Il, of noncorrosive material, may be interposed, as above explained and iu the same manner, into contacting relation with the resistance stick or rod A.

Having now set forth the object and nature of my invention and various constructions embodyingtheprinciples thereof,what I claim as new and useful and of my own invention, and desire to secure by Letters Patent, is-

l. In a combined electric rheostat and heater, a stick or rod of resistance material having openings therethrough at various intervals, non corrosive contacts, and means passing through said openings for securing said contacts to said rod, as and for the purpose set forth.

2. In a combined electric rheostat and heater, a non-metallic stick or rod forming the resistance material, non-corrosive contacts, and pins or studs passing through said stick or rod for clamping said contacts thereto, as and for the purpose set forth.

In an apparatus of the class described, an insulating-plate, a resistance stick or rod mounted thereon, a series of contact-points,

a series of non-corrosive contacts applied to said stick or rod and each in electrical c0nnection with a contact-point, and a contact arm or lever operating over said contactpoints, as and for the purpose set forth.

f. In an apparatus of the class described, an electric circuit including a pivoted contact arm or lever, a resistance stick or rod, a series of nou-corrosive contacts in electrical connection therewith, said contact arm or lever operating over said contact-points, whereby the resistance of said arm may be varied, as and for the purpose set forth.

5. In an apparatus of the class described, an velectric circuit including a pivoted contact arm or lever, a resistance stick or rod, a series of contact-points in independent electrical connection therewith, said contact arm or lever operating over said contact-points, and an automatic retaining device or detent operating to engage and lock said arm or lever, as and for the purpose set forth.

G. In an apparatus of the classdescribed, a resistance stick or rod, an opening formed therethrough, a pin or stud arranged to pass through said opening and provided at one end with a head audhavingits other end threaded,- a nut mounted upon said threaded end and operating to clamp said pin or stud to said resistance-stick, and a contact-point in electrical connection with said pin or stud, as and for the purpose set forth.

'7. In an apparatus of the class described, a non-metallic resistance stick or rod having an opening therethrough, a pin or stud passing through said opening and provided with a head at one end and threaded at the other IOO end, :L uut mounted upon Said threaded end, l hund,this Qdday of October, 1901, in the preszmd non-corrosive Contact Washers or plates ence of the subscribing Witnesses. interposed between said head :md nut and f E F said stick or rod, and a contact-point iu eleo- I MAX C KRU G JR' 5 trioal connection with said pin or stud, as and Vitnesses:

for the purpose set forth. C. H. SEEM,

In witness whereof I have hereunto set my l S. E. DARBY. 

